This invention relates to methods and apparatus for increasing the capacity of present and future satellite communications systems. It relates particularly to methods and apparatus for increasing the capacity by making more bandwidth available by means of reuse (by either partial or complete overlap) of frequency bands.
The cost to launch a communications satellite is substantial. The cost is generally considered to be in excess of thirty million dollars per satellite. For that reason, and because there are only a limited number of satellites presently available for communications systems, it is desirable to increase the utilization of satellites.
The total bandwidth available for use with any given satellite is also a limited, finite amount.
In the conventional, prior art satellite communications systems each earth station transmits a signal in a unique given frequency band, and in particular in a band different from that used by a correspondent station (a station receiving the signal transmitted by the first earth station).
Since there are the limitations, as noted above, on the amount of bandwidth available for communication systems using satellites, there is also a limitation on the number of pairs of earth stations that can communicate with one another.
Since there is a large demand for the use of satellite communications sytems, there are more potential users who want to use satellite communications systems than there is bandwidth available for such users.